But Harrington says that the same techniques used to soothe a fussy baby can also help an infant overcome the pain of vaccinations.

"It probably generates more pain than you or I have when we get a shot," says Harrington, a researcher at Children's Hospital of the King's Daughters in Norfolk, Va., because infants are so much smaller.

Harrington wanted to find a way to ease the pain and stress of a shot. So he studied 230 infants, who were two months old and four months old. He divided them into four groups. Two groups got water before a vaccination, while the other two got a sugar solution, a sort of liquid lollipop known to distract infants from pain. After the shot, half the babies got typical comfort care from their parents. The others received the "5 S's".

That's a method that Harvey Karp, a Los Angeles-based pediatrician, developed about a decade ago to calm a screeching infant. The technique involves swaddling the baby, putting the baby on her stomach, gently swinging her, shushing into her ear, and offering a pacifier to suck on.

The babies who received the "5 S's" physical intervention stopped crying much sooner than the infants who received comfort care from their parents. And their pain scores, as measured by flailing arms and facial grimaces, were also significantly less, says Harrington. The "5 S's" group did much better than the comfort care group, whether they got sugar water or not.

The results were published in the journal Pediatrics.

A parent demonstrates the "5 S's" soothing technique.

Karp says the method works because it simulates the security of the womb. "In the womb, there's a symphony of sensations, constant jiggling, constant whooshing, which is the sound of the blood flow through the arteries, and constant touching against the velvet walls of the womb."

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